A comparison of daily fluoride intakes from food samples in Japan and Brazil

The purpose of this study was to analyse the fluoride content of Japanese infant foods and foods in Brazil and to estimate daily fluoride intake calculated for a 6-month-old infant which reflects supplemental fluoride increased from infant foods and decreasing breast-feeding and commercial milk-feeding. Fluoride concentrations of 26 samples were assessed by a modified microdiffusion method and fluoride ion selective electrode. The fluoride content varied from 0.53 to 1.33 microgram/g for milk-base formulas, from 0.46 to 2.94 micrograms/g for infant foods in Japan, and from 0.06 to 0.25 microgram/g for foods in Brazil. The daily fluoride intake was calculated according to feeding pattern. The minimum and maximum fluoride values were 0.080 mg/day and 0.248 mg/day, respectively. These fluoride intakes, expressed in milligrams per kg of fluoride intake, ranged from 0.010 to 0.033 mg F/kg body weight. No significant differences in fluoride intake values were found between Japanese infant foods and foods in Brazil. The results of this study indicate that daily fluoride intakes of Japanese infant foods and foods in Brazil could be considered within the optimal recommended level.     

Effect of low fluoride dentifrices on microhardness of sound enamel. In vitro study

The present study was undertaken to evaluate the effect of dentifrices containing low fluoride concentrations on microhardness of sound enamel in 50 healthy young premolar teeth. They were divided into five different groups according to the concentrations of fluoride in dentifrice used. The Vickers hardness of enamel was measured using a Zwick microhardness tester under 1000 g load and a Vickers indenter before and after the application of fluoride dentifrices. The results of the present study suggest that low fluoride concentration dentifrices are as effective as the higher concentrations in increasing the hardness of enamel.     

Nicotine in the crude synaptosomal fraction of the rat brain

The in vitro uptake of nicotine into the crude synaptosomal fraction of rat brain and spinal cord was studied. The tissue/midium ratio was low and the changing of incubation time or [14C]nicotine concentration did not affect the ratio, nor did a metabolic inhibitor, sodium fluoride. A lowered ratio was obtained at 0degrees C, but this decrease may be attributable to an altered pKa of the drug at low temperature. Nicotine antagonists, mecamylamine and hexamethonium, did not affect the ratio when incubating the crude synaptosomal fraction of either adult or infant rat brain. These results suggest that the uptake of nicotine into the synaptomal fraction is not an active process. When mecamylamine and nicotine were injected in vivo, the mecamylamine antagonism was also demonstrated as lowered nicotine concentrations in infant ray synaptosomes. Since the newborn rat cortex lacks glial tissue, the nicotine concentrations in the crude synaptosomal fraction of infant rats may reflect the receptor level effects better than in adult brains. The pretreatment of infant rats with mecamylamine also lowered blood nicotine levels, suggesting that mecamylamine affected nicotine brain levels also in an unspecific way.     

Methoxyflurane biotransformation and renal function following methoxyflurane administration for vaginal delivery or cesarean section

Methoxyflurane (MOF) administration for conscious analgesia during vaginal delivery (range 5 to 70 min, mean 23 min) or for anesthesia following delivery of the infant at cesarean section (range 25 to 70 min, mean 44 min) was studied in 18 healthy parturients. Serum ionic fluoride increased significantly in both groups 2 hours after discontinuing MOF with peak concentrations of 11.2 and 14.1 mumol/L in the vaginal delivery and cesarean section groups, respectively. Individual peak serum ionic fluoride levels in the 2 groups of 21 and 25 mumol/L were well below reported levels for subclinical toxicity. Significant ionic fluoride elevations in fetal umbilical venous blood (mean 5.3 mumol/L) were measured in the vaginal-delivery group. Maternal urinary ionic fluoride and oxalate were elevated 24 and 48 hours postpartum. BUN, creatinine, urine volume, and urine osmolality remained within normal range. These data indicate that hazardous elevations of serum ionic fluoride with subsequent renal dysfunction are unlikely following low-dose MOF administration for vaginal delivery or cesarean section.     

Selenate fortification of infant formulas improves the selenium status of preterm infants

The purpose of this study was to determine whether selenate fortification of infant formula would improve the selenium status of relatively well, growing, preterm infants during the first 12 wk of enteral feeding. A high-selenium group (n = 7, mean body weight = 1312 g) received selenate-fortified preterm and full-term infant formulas containing 0.36 and 0.22 mumol Se/L, respectively, and a low-selenium group (n = 10, mean body weight = 1262 g) received non-selenium-fortified preterm and full-term infant formulas containing 0.12 and 0.11 mumol Se/L, respectively. There were no significant differences in growth between the two groups throughout the study. The high-selenium group had significantly greater mean selenium intakes than did the low-selenium group from weeks 2 to 12. Plasma selenium concentrations decreased over the study period in the low-selenium group. Plasma selenium-dependent glutathione peroxidase activity was greater in the high-selenium group at week 12 only. Red blood cell selenium concentrations decreased over time in both groups and were significantly greater in the high-selenium group at weeks 4, 8, and 12. Plasma selenium concentrations were significantly correlated with plasma glutathione peroxidase activity for all infants on study day 1 and at weeks 4 and 12. Selenium intake of all infants was significantly correlated with plasma glutathione peroxidase activity at 12 wk. Selenate fortification of infant formulas can improve the selenium status of preterm infants. Current selenium contents of infant formulas and recommendations for dietary intakes of selenium for some preterm infants may be inadequate.     

The effects of fluoride concentration and the level of cariogenic challenge on caries development in desalivated rats

Dental caries is an infectious and transmissible disease that continues to affect the majority of people. The presence of carbohydrate, mainly sucrose in the diet, is an important factor in its occurrence. The amount of fluoride required for optimal protective effect where there is a high caries challenge is unclear. Differences in the intensity of cariogenic challenge, for whatever reason, may play a part in determining fluctuations in the effectiveness of fluoride. The purpose of this study was to evaluate the effect of different concentrations of fluoride on the development of caries and explore the cariostatic effect of fluoride under various levels of cariogenic challenge. The study comprises two experiments. In experiment I, 60 desalivated Sprague Dawley rats infected with Streptococcus sobrinus were offered the following to drink for 21 days: group (1), sterile distilled water (SDW); (2) 10 parts/10(6) F SDW; (3) 20 parts/10(6) F SDW; (4) 30 parts/10(6) F SDW; (5) 40 parts/10(6) F SDW. In experiment II, eight groups of 9 rats were placed in a K?nig H?fer programmed feeder and were exposed to different levels of cariogenic challenge through varying frequency of eating and offered water containing 10 parts/10(6) F. In experiment I, exposure to 20, 30 and 40 parts/10(6) F reduced caries development significantly: fluoride, at 10 parts/10(6), reduced the severity of the carious lesions. In this model of severe cariogenic challenge, the results suggest that elevated concentrations of fluoride might be effective in patients at high caries risk. In experiment II, fluoride reduced the incidence and severity of smooth-surface caries in all groups. The protective effect of fluoride decreased as the number of exposures to sugar increased. It is concluded that the effectiveness of fluoride is influenced by the level of cariogenic challenge and that consideration should be given to adjusting the level of fluoride exposure based on perceived caries risk, and that there is a maximum therapeutic effect of fluoride beyond which no additional protection can be expected.     

Predominant serovars of Salmonella in humans and foods from Thailand

During the period from 1993 to 1996, a total of 27,497 Salmonella isolates from humans, chicken meat, ready-to-eat Thai foods and shrimps were serotyped to know the predominant serovars of Salmonella in humans and foods in Thailand. Seventy-two and 81 serovars of Salmonella were identified in human and food samples, respectively. The significance of foods as a vehicle for human salmonellosis was discussed from an epidemiological viewpoint.     

World trends in infant feeding

Analysis of the dyadic nature (nutritional, psychological, and biological interaction between mother and infant with each affecting the other) and the economics of infant feeding strongly suggests the superiority of breastfeeding over artificial feeding, regardless of the socioeconomic status of societies. Universally, there are 3 main guidelines for scientifically guided biological infant feeding: 1) to feed the pregnant and lactating mothers with a mixed diet of locally available foods; 2) to breastfeed alone for 4 to 6 months, and 3) to introduce least cost weaning foods based on the concept of multimixes from 4 to 6 months onward, preferably prepared from locally available foods but with continuing lactation into the second year of life, particularly in poorer circumstances. Widespread increases in breastfeeding will protect some 10 million infants annually against marasmus and diarrheal diseases, some 1 million cases against infantile obesity and 100,000 cases against cow's milk allergy. The basic issue involved is the development of practical programs which would improve the pattern of breastfeeding or at least minimize its decline, and to optimize the quantity and quality of milk production, particularly by maternal feeding. This can be done by instituting changes in the emphasis in the education of health professionals, and in procedures at pediatric wards and maternity units in hospitals. The promotion and advertising of infant formulas, especially in poor areas, needs monitoring, and appropriate legislation and enforcement. Lactating mothers who are working should be provided with bonuses, creches, 'nursing pauses' in industry, and other methods which will encourage them to combine the roles of motherhood and salaried worker effectively. Interdisciplinary undertakings between economists, administrators and health professionals are needed in order to improve breastfeeding patterns on a community basis. Reappraisal of modern infant feeding practices should be based on modern scientific knowledge, awareness of successful traditional time-tested adaptation, and on man's ancient biological mammalian heritage.     

Estimated content percentages of volatile liquids and fat extractables in ready-to-eat foods

Content percentages of volatile liquids and fat extractables in 340 samples of ready-to-eat foods were determined gravimetrically. Volatile liquids were determined by drying samples in a microwave oven with a self-contained balance; results were printed out automatically. Fat extractables were extracted from the samples with mixed ethers; extracts were dried and weighed manually. The samples, 191 nonfat and 149 fatty (containing ca 2% or more fat) foods, represent about 5000 different food items and include infant and toddler, ethnic, fast, and imported items. Samples were initially prepared for screening of essential and toxic elements and chemical contamination by chopping and mixing into homogenous composites. Content determinations were then made on separate portions from each composite. Content results were put into a database for evaluation. Overall, mean results from both determinations agree with published data for moisture and fat contents of similar food items. Coefficients of variation, however, were lower for determination of volatile liquids than for that of fat extractables.     

The effect of fluoride on Streptococcus sanguis 7863 IgA1 protease production and activity

Fluoride was found to affect the production of the bacterial IgA1 protease but to have no effect on IgA1 protease activity. The concentrations of fluoride that do affect Streptococcus sanguis growth and IgA1 protease production are higher than those normally seen in vivo under normal circumstances. The concentrations of fluoride in dental plaque following use of a fluoride rinse or dentifrice would be sufficient to reduce Strep. sanguis IgA1 protease production.     

Professional courtesy--ethics and the law in the medical treatment of physicians and their families

Children's toothpastes with fluoride help to prevent decay, but parents should ask their dentist before giving fluoride supplements to children. Overdosage is harmful. Sugars eaten as part of a meal do less harm to teeth than those eaten frequently as snacks. Sugar-free infant drinks and children's confectionery are now on the market and are more "tooth friendly". Look out for the "happy tooth" symbol. Babies can be registered with NHS dentists as soon as the first teeth start to come through, and should be taken regularly to the dentist throughout childhood. Under the NHS scheme, dentists are paid a capitation fee to provide continuing preventive care and treatment for children free of charge.     

Association of calponin with desmin intermediate filaments

Our previous immunoelectron microscopy studies of chicken gizzard smooth muscle cells showed that in certain areas the distribution of anti-calponin exhibits a high degree of overlap with beta-actin, filamin, and in particular, desmin, suggesting that in situ a fraction of calponin may be associated with intermediate filaments of the cytoskeleton. In this work we further explore this idea by studying the interaction between calponin and desmin. We found that at physiological salt concentrations, calponin bound only weakly to synthetic desmin intermediate filaments. On the other hand, calponin bound strongly to nonfilamentous desmin tetramers and was incorporated into intermediate filaments when the two proteins were mixed in a buffer containing 6 M urea and dialyzed into a buffer containing 0.15 M NaCl. Anti-calponin was found to label a portion of intermediate filaments and dense bodies isolated from gizzard tissues. Our findings suggest that in chicken gizzard smooth muscle cells, calponin may be an integral component of desmin intermediate filaments in the vicinity of dense bodies. Since calponin is also known to bind actin, we hypothesize that one of the functions of calponin might be to bridge intermediate filaments with actin in dense bodies.     

Absorption of zinc from lupin (Lupinus angustifolius)-based foods

The absorption of Zn from a lupin (Lupinus angustifolius) milk fortified with Ca, a bread containing lupin flour (230 g/kg), a sauce containing lupin flour and a sauce containing a lupin-protein isolate was determined in humans by measuring the whole-body retention of radioisotope from meals labelled with 0.02 MBq 65Zn, allowing for endogenous excretion of Zn, after 14 d. The absorption of Zn from the Ca-enriched milk (16.2%) and the bread made with lupin flour (27.0%) was similar to literature figures for comparable soya-bean products. The absorption from composite meals made with lupin flour (28.2%) and protein isolate (32.7%) was significantly higher than that reported for comparable soya-bean products. In a second experiment the absorption of Zn from a lupin-milk base and a soya-bean-milk base was compared with that from Ca-supplemented bases. The absorption of Zn from the lupin-milk base (26.3%) was significantly higher than from the soya-bean-milk base (17.6%), and neither was significantly altered by the addition of Ca. Overall the absorption of Zn from lupin-protein foods was found to be higher than from comparable soya-bean products. Lupin milk could be an attractive alternative to soya-bean milk for infant formulas.     

The effect of bicarbonate/fluoride dentifrices on human plaque pH

The acidogenic response in dental plaque after rinsing with sodium bicarbonate/fluoride dentifrice slurries was studied using three intra-oral models. In the first model, resting plaque pH was monitored in mesiobuccal plaque on upper molars and premolars in six healthy subjects after abstinence from normal oral hygiene for three days. These measurements were followed by a three-minute rinse with 10% sucrose and, following a two-minute interval, a three-minute rinse with a test dentifrice slurry. After the test dentifrice rinse, pH was monitored at regular intervals up to 60 minutes. Flow rate, pH and buffer capacity of stimulated saliva were also determined. Changes in resting pH, plaque pH minima, and maximum pH drop were calculated. A clear elevation in the resting pH was observed after bicarbonate/fluoride dentifrice rinses, and a significant increase was obtained in the pH minima. The smallest pH drop also was found after treatment with the bicarbonate/fluoride dentifrice rinse treatment (p < 0.02). A second model using telemetric partial dentures with interproximally placed micro-antimony pH electrodes was used to study the effects of rinsing with increasing concentrations of sodium bicarbonate and calcium carbonate solutions, and with a fluoride dentifrice containing sodium bicarbonate. The response to these treatments was found to be rapid, dose-dependent, and was the greatest from the sodium bicarbonate. A third model used 24 subjects to assess the effects of sodium bicarbonate/fluoride dentifrice on plaque pH before and after a glucose challenge. The use of the bicarbonate/fluoride dentifrice resulted in significantly less measurable plaque acid than the fluoride dentifrice treatment. Collectively, these results indicate bicarbonate in dentifrice to be an effective buffering agent for stabilizing the pH and neutralizing plaque acids in dental plaque.     

Modulation of synaptosomal plasma membrane-bound enzyme activity through the perturbation of plasma membrane lipid structure by bupivacaine

To determine whether young capuchin monkeys, Cebus apellaselectively interacted with others concerning novel foods, 11 infants (4.5-12 months) living in two groups were observed following presentation of familiar or novel foods. Foods were presented either to the whole group or to infants in a section of the home cage to which only they had access. Infants showed more frequent interest in others' food and picked up foods more frequently when foods were novel, and they tended to eat novel foods more frequently than familiar foods. The pattern was the same whether the foods were presented to the group or only to infants. Infants expressed interest in others' novel foods equally often before and after sampling these foods themselves. The frequency of interest in others' food correlated positively with age. It is concluded that acceptance of novel foods in these monkeys occurs readily regardless of socially provided information about edibility. Social interactions do not appear to make important contributions to acceptance of novel foods by infant capuchin monkeys.     

膜过滤处理含氟工业废水

处理高浓度含氟工业废水,通常采用的中和反应沉淀法比较复杂,中和反应生成的氟化钙颗粒微小,常规沉淀不能完全析出,出水氟含量容易超排放标准（10 mg/L）。应用表面膜过滤技术处理酸性含氟废水能克服这些弊端,可以处理废水中顽固的氟化物、金属离子和悬浮物等,而且该处理系统具有自动化程度高、稳定性高、操作简便、占地面积小和运行费用低等优点,处理后的水清澈,含氟量、金属离子和悬浮物远低于排放标准。     

Growth of Floating Aquatic Macrophytes in Alkaline Industrial Wastewaters

Ponds holding industrial wastewater can quickly develop algal blooms, which in turn results in high pH excursions. Such deterioration in water quality is experienced in Portland Aluminium's retardation pond. A covering of floating aquatic plants, such as Azolla filiculoides and Lemna minor, will reduce the light entering the water body, in turn reducing algal production and lowering pH levels. In the case of Portland Aluminium's retardation pond, the initial installation of such a system has to be established under alkaline conditions and in high fluoride concentrations (up to 10 mg∕L). The survival and growth of A. filiculoides and L. minor under alkaline conditions (pH levels of 7–9.5) and under different fluoride concentrations (0–10 mg∕L) were assessed in the laboratory and in field conditions. L. minor grew well under alkaline and high fluoride conditions in short-term laboratory tests, but appeared unable to compete with itinerant algae in the field. A. filiculoides survived only in media of pH 7 and 0-mg∕L fluoride in the short-term laboratory tests, but grew very well in the long-term field experiments. A. filiculoides was also observed to inhibit algal growth in the field. Both species absorbed fluoride. Fluoride concentrations in the plants rose and fell in relation to the fluoride concentrations in the pond, suggesting that the fluoride was readily desorbed and that the absorption itself was by a passive mechanism.     

Evaluation of fluoride uptake by enamel in children from fluoride dentifrices

Fluoride dentifrices are well accepted for their caries preventive effects. Although it is generally accepted that the presence of fluoride in the enamel protects teeth against carious attack, at the same time, there is some concern that ingestion of fluoride from toothpastes may substantially contribute to the total intake of this element. The present study was undertaken to clinically evaluate the fluoride uptake by human enamel after the use of lower concentrations of fluoride dentifrices and compare their potency to higher concentration in increasing the uptake of fluoride by enamel. Enamel biopsy was conducted on first permanent molars of 100 school children, aged 6-8 years before brushing and at intervals of one hour, 3 weeks, 6 weeks and 12 weeks following brushing with different concentrations of fluoride dentifrices. The fluoride content of the enamel biopsy samples were estimated using the Orion microprocessor ion analyser and by taking into consideration the enamel biopsy mass and depth of the etch. The results of the present study suggest that low fluoride concentration dentifrices provide similar fluoride uptake by enamel when compared with that of higher concentrations.     

Clinical evaluation of sodium fluoride chewable tablets in dental caries

Chewable tablets containing low dosage fluoride content were prepared using two varieties of celluloses and their in vitro parameters were evaluated. An eighteen month clinical trial revealed that both these formulations were effective in controlling the caries. However, ethyl cellulose is proved to be superior to methylcellulose as a controlled release matrix material in controlling caries. Thus this study recommends ethylcellulose matrix tablets containing low fluoride content is an efficacious and cost effective drug device in controlling dental caries.